These studies explore the factors that affect oxygenation of the fetus-in-utero. We are studying the dynamics of the fetal circulation experimentally in sheep. We are developing mathematical models of the fetal circulation and oxygen transport. We are comparing the effects of steady state vs. intermittent hypoxia on fetal survival in rabbits. We are simulating the effects of labor contractions in causing intermittent hypoxia in these studies. We are studying the transfer of water and carbon dioxide across the placenta. These studies have clinical implications in abortions, still births and neonatal deaths, birth defects, cerebral palsy and various psychomotor disturbances.